To calculate on-time graduation, the same cohort of students is tracked throughout high school. Those who graduate with their class 4 years after beginning 9th grade are counted as graduating “on time.” To graduate in 2011-12, students had to pass high school proficiency exams in reading and writing; by 2015, requirements for passing math and science end-of-course exams had been added.

In King County overall, 80% of students in the Class of 2016 graduated on time (in 4 years, with the same cohort of students with which they started high school).However, the proportion of King County students who started high school in the 2012-2013 school year and graduated with their class in 2016 varied by gender, race/ethnicity, English language proficiency, homelessness, special education status, and family income (students who qualified for free or reduced-price school meals were considered low-income).

On-time graduation rates for Blacks, Native Hawaiians/Pacific Islanders, Hispanics, and American Indians/Alaska Natives were all at or below 70%, trailing the rates for Asians (88%) and whites (85%) by at least 17%.

78% of males graduated on time, compared to 83% of females.

56% of students with limited English proficiency graduated on time.

59% of special education students graduated on time.

52% of homeless students graduated on time in 2016, up from 36% in 2013.